H2Tech - Q4 2021 - 46

HYDROGEN STORAGE
significantly reduced the size and capacity per unit. In the case
of electrolysis, polymer electrolyte membrane (PEM) is favored
for energy storage applications vs. alkaline electrolysis, which has
been used commercially since the 1940s, is a comparatively mature
technology and is (currently) more efficient (72%). PEM
maintains its efficiency when partially loaded, it has a lower current
density, it operates at low pressure (< 30 bar, < 580 psi) and
temperature (50°C-80°C, 122°F-176°F), it has a smaller physical
footprint per MW, and it can ramp up more quickly.10
At present,
commercial PEM electrolyzers have an electrical energy efficiency
of 64% vs. a theoretical efficiency of 86%.
It is expected that the rapid expansion of electrolyzer manufacturing
capacity worldwide will result in a substantial reduction
in the unit cost of electrolysis, by as much as 65% by 2025,
and increase the diversity of suppliers.11,12
The cost of alkaline
electrolyzers may also benefit from economies of scale.13
Generation. The combustion of blends of natural gas and
H2 for power is a mature technology. Cogeneration using highH2
fuels in the coking and refining industries dates to the 1950s.
The supply chain and operating and maintenance support for
combustion engines and turbines is well established and reliable.
Depending on required ramp-up time and output requirement,
using available technology at normal operation can fire
on 80%-100% H2
and 0%-20% pipeline gas for flame stability.
At present, thermal generation technologies available with performance
guarantees are small units (2 MW-3 MW); however,
nearly all major thermal generation equipment suppliers will
warranty performance on existing technologies firing on 30%-
65% H2
and forecast certifying various products for 100% H2
service by 2025-2030.
Integration of operations. Since 1988, more than 140
power-to-gas projects have been completed worldwide, includGas
supply
ing 102 power-to-H2 projects.14,15
Of these, 10 are substantive
projects demonstrating the integration of renewal generation
and electrolysis and/or geologic storage. Among these 10 projects,
six also feature integrated power generation.
Geologic storage of H2
. Naturally occurring geologic salt has
. Consequently,
the unique characteristic of behaving plastically, which makes it
effectively impermeable to gases, including H2
natural occurring salt bodies in the subsurface are widely used
for storage of natural gas (44 facilities in N. America), and more
than 500 caverns are used for the storage of propane, butane,
ethane and mixed grades of natural gas liquids. One helium
storage cavern facility is operated by the U.S. Bureau of Land
Management, and several others are operated by the Russian
government for storage of H2
and O2
town gas (60% H2
. Utilities in the U.S. and
Germany operate three salt caverns for compressed air storage.
High H2
) was first stored in salt at two
locations in Germany (TABLE 8), but both locations later converted
the caverns to natural gas service. Subsequently, four H2
storage facilities using salt caverns have been put into service,
primarily to support petrochemical use of H2
capacity of existing facilities is 8.5 Bsft3
Unlike salt, geologic storage of H2
. The combined
.
, or 20.468 MMkg of H2
has not been attempted at
commercial scale in porous rocks, and concerns remain about
H2
-rock mineral reactions have been
and some reservoir-specific inbut
detailed core testing
-rock chemical reactions, subsurface microbial contamination,
and top seal integrity. H2
evaluated at a general level,18,19
vestigations have been reported,21-23
under burial conditions and in the presence of subsurface fluids
have not been widely performed. Ongoing field tests, such as
geologic storage of H2
in porous reservoirs, are being investigated
by a number of projects.
TABLE 7. Renewable energy facilities integrating two or more HES component systems
Name, location (start year)
Magnum, Utah, U.S. (2025)
Storage
HYFLEX Cogen, France
(2022 startup)
Sun Storage (PV solar),
Austria (2015)
Falkehhagen,
Germany (2013)
Myrte PV Solar Corsica,
France (2012)
Gaines Cavern Wind
Project, Texas, U.S. (2012)
Hybrid-Kraftwerk (wind),
Germany (2011)
Wind2H2, Boulder,
Colorado, U.S. (2010)
Hércules PV plant,
Spain (2006-2010)
Hychico Wind Farm,
Argentina (2008)
Utsira Wind,
Norway (2004)
46 Q4 2021 | H2-Tech.com
Hydrogen alkaline electrolyzer
Hydrogen 12-MW PEM electrolyzer
Hydrogen 0.6-MW alkaline electrolyzer
Hydrogen 2-MW PEM electrolyzer
Hydrogen 50-KW PEM electrolyzer
Compressed air
Hydrogen 0.5-MW alkaline electrolyzer
Hydrogen 33-KW PEM electrolyzer
Hydrogen 60-KW PEM electrolyzer
Hydrogen 4-MW PEM electrolyzer
Hydrogen 55-KW PEM electrolyzer
Bedded salt
(Not announced)
Depleted gas reservoir
Pipeline phase III: Salt cavern
Tube tank
Salt cavern (150 hr)
Tube tank
Tube tank
Tube tank
Tube tank reservoir storage
Tube tank
1.4-MW gas engine
10-KW fuel cell
100-KW PEM fuel cell
Turboexpander
Gas engine
(Mobility fuel)
Generation
J-class turbine
Siemens SGT-400
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